It's brand specific and sometimes model specific. Different manufacturers use different methods of measure up for size. The only way to tell is to throw your leg over the thing. However, as you get a bit of experience, you'll start to get a feel for the numbers.

There are size calculators on in the internet - they've been linked to before on here so a quick search won't hurt, but don't take them as gospel.

Looking at the review pane, I see Europas got in first The quick and nasty way:
Stand over the top tube, feet flat on the floor. Is there 30-50 mm of space between the boys and the frame? If so, sit on it and grab the bars. Are you too cramped or stretched? If not, it's test ride time

As an example of company sizing, I have a Giant MTB and Roadie, the MTB is sized 17inch and fits, the Roadie is sized 50cm and fits

I'm a bit shorter than Mike (178 cm) and I find that 56 cm seat tubes / top tubes are about right too.
The boys might beg to differ, because that doesn't give them a lot of clearance on a traditional frame!

These slanting top tubes make it hard. In the good old days, of horizontal top tubes and not a lot of choice in frame sizes anyway, it was fairly easy. But there's more choice now and with the top tube doing all sorts of weird things, you have to look very carefully at reach as well as height.

Don't buy on the numbers. Stand over the top tube and see how high you're voice'll be if you slip off the seat. Sit on or ride the bike and see how far you have to reach (or not). That's the only way to tell. The major revisions I had to do to the Sow's Ear to get her to fit indicate it can be done with a too small frame, but it's not pretty and not good.

Who is online

About the Australian Cycling Forums

The largest cycling discussion forum in Australia for all things bike; from new riders to seasoned bike nuts, the Australian Cycling Forums are a welcoming community where you can ask questions and talk about the type of bikes and cycling topics you like.